Halfway Between 4 and 21

When you ask "What number is halfway between 4 and 21?" we assume you mean the number in the exact middle of the two numbers on a number line, as illustrated below, where X=4 and Y=21.

Halfway Between Line

To find the number halfway between 4 and 21, we use the following formula:

(X + Y)/2 = Halfway Between

When we enter 4 and 21 into our formula, we get:

(4 + 21)/2 = 12.5

Thus, the number halfway between 4 and 21 is 12.5.

To check that our answer is correct, we subtract 4 from 12.5 and subtract 12.5 from 21 and compare the two numbers:

12.5 - 4 = 8.5
21 - 12.5 = 8.5

As you can see, the halfway number is 8.5 higher than 4 and 8.5 lower than 21. Therefore, our halfway between answer of 12.5 above is correct.

Halfway Between
Find halfway between two other numbers here!

Halfway Between 4 and 22
Here is our next Halfway Between calculation.